• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1401-1403
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• 1998

The composition, weight decrease, DTA, and surface structure of vinyl insulated wire with thermal treatment conditions have been investigated. The composition of Cu by EDX analysis indicates Cu, Cl, and O lines, and oxidation reaction results from thermal treatment. Thermal treated IV and HIV appeared chemical reaction at $269^{\circ}C$ and $265^{\circ}C$, respectively. SEM of thermal treated Cu at $250^{\circ}C$ disappears an elongation structure, and appears an original structure.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.77-84
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• 2006

For a fire cause judgement this paper describes the heating characteristics of electric bare wire melted by AC current. The cower wires prepared for the experiment were 1.2[mm], 1.6[mm], and 2.0[mm] in diameter. Through the cross section analysis(CSA), it was confirmed that the dendrite structure grew at the angle of about 40[$^{\circ}$] or 60[$^{\circ}$] when the fusing current was applied to the wires. The larger the fusing current is, the more decreased the growth angle of the dendrite structure is. It was confirmed that the dendrite structure was arranged like the columnar structure.

• Smart Structures and Systems
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• v.25 no.3
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• pp.311-322
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• 2020

This paper studies the influence of parameters of a novel SMA helical spring energy dissipation brace on the seismic resistance of a frame structure. The force-displacement relationship of the SMA springs is established mathematically based on a multilinear constitutive model of the SMA material. Four SMA helical springs are fabricated, and the force-displacement relationship curves of the SMA springs are obtained via tension tests. A numerical dynamic model of a two-floor frame with spring energy dissipation braces is constructed and evaluated via vibration table tests. Then, two spring parameters, namely, the ratio of the helical spring diameter to the wire diameter and the pre-stretch length, are selected to investigate their influences on the seismic responses of the frame structure. The simulation results demonstrate that the optimal ratio of the helical spring diameter to the wire diameter can be found to minimize the absolute acceleration and the relative displacement of the frame structure. Meanwhile, if the pre-stretch length is assigned a suitable value, excellent vibration reduction performance can be realized. Compared with the frame structure without braces, the frames with spring braces exhibit highly satisfactory seismic resistance performance under various earthquake waves. However, it is necessary to select an SMA spring with optimal parameters for realizing optimal vibration reduction performance.

• Coupled systems mechanics
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• v.5 no.2
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• pp.191-201
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• 2016

Coupled structures are widely seen in civil and mechanical engineering. In coupled structures, monitoring the translational motion of its key components is of great importance. For instance, some coupled arms are equipped with a hydraulic piston to provide the stiffness along the piston axial direction. The piston moves back and forth and a distance sensing system is necessary to make sure that the piston is within its stroke limit. The measured motion data also give us insight into how the coupled structure works and provides information for the design optimization. This paper develops two distance sensing systems for coupled structures. The first system measures distance with ultrasonic sensor. It consists of an ultrasonic sensing module, an Arduino interface board and a control computer. The system is then further upgraded to a three-sensor version, which can measure three different sets of distance data at the same time. The three modules are synchronized by the Arduino interface board as well as the self-developed software. Each ultrasonic sensor transmits high frequency ultrasonic waves from its transmitting unit and evaluates the echo received back by the receiving unit. From the measured time interval between sending the signal and receiving the echo, the distance to an object is determined. The second distance sensing system consists of a wire draw encoder, a data collection board and the control computer. Wire draw encoder is an electromechanical device to monitor linear motion by converting a central shaft rotation into electronic pulses of the encoder. Encoder can measure displacement, velocity and acceleration simultaneously and send the measured data to the control computer via the data acquisition board. From experimental results, it is concluded that both the ultrasonic and the wire draw encoder systems can obtain the linear motion of structures in real-time.

• Fire Science and Engineering
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• v.14 no.3
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• pp.1-5
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• 2000

In this paper, we analyzed the fire hazard of the ballast for fluorescent lamp used as the indoor lighting. In the result of being analyzed the ballast wire by stereo microscope, many melting points were discovered, it was impossible to judge a cause with the naked eye. In the Thermal-deteriorated ballast wire, elongation structure disappeared at above $700^{\circ}$, and it only showed the enlarged appearance of the copper particle. On the metallurgical microscope of short wire, as it was confirmed the regulation of the columnar structure and the void growth at the center of boundary-face, we found that electrical short-circuit generated. Also, it was confirmed the melted part on the analysis using SEM(scanning electron microscope). Not only CuL and Cuk line that is composition factor of copper but also OK line was observed uniformly on the spectra analysis using EDX(energy dispersive x-ray spectroscopy). It means that oxygen took part in reaction at the recombination process.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.1
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• pp.78-85
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• 1999

Burning characteristics of solid propellants embedded with four kinds of metal wires(Ag, Cu, Al, Ni-Cr wire) were studied with varying wire diameters(O.10.8 mm) lot N-5 propellant. It was found that the order of the burning rate increment ratio($r_w$/$r_sb$) was Ag wire > Cu wire > Al wire> Ni-Cr wire which was the same as the order of the magnitude of thermal diffusivity. The burning rate increment ratio($r_w$/$r_sb$) of N-5 propellant was less than that of composite Propellant because of the difference of adiabatic flame temperature and flame structure. When Ag, Cu and Al wire having high thermal diffusivity were embedded in N-5 propellant, the plateau and mesa characteristics of the double base propellant were disappeared, but not disappeared in the case of propellant embedded with Ni-Cr wire due to its poor thermal conductivity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.1
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• pp.3-8
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• 2011

This paper introduces a robot eye module, of which two degree-of-freedom motions, i.e. panning and tilting, are driven by a pair of wires. The main feature of the module is that each wire can generate push-pull motion without buckling. It is thanks to a Teflon tube which guides the path of the moving wire. End points of the tube and wire have pivot elements so that a smooth push-pull motion is produced even when the end point of wire is moved by eye rotation. This mechanism helps the eye module to be very compact. In this paper, the structure of the robot eye module is introduced in detail, and the required motor angles for a certain direction of eye line are investigated analytically and experimentally.

• Structural Engineering and Mechanics
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• v.44 no.2
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• pp.239-255
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• 2012

This work presents a contribution to understand the inverted trussed beams behavior. The system has a main beam and struts with rectangular cross section associated to a wire rope enlaced to the main beam. It is an unpublished system with the advantage of easy positioning of the wire rope, once it is a continuous and connected by turnbuckles. It is a system that can be used as support for concrete formworks or for rehabilitation wooden beams proposal. The enlacement of the cable demands a small notch at the top of the cross section and a cross pin at the bottom. Six inverted trussed beams were tested, with spans of 180 cm with cables diameter of 1/4". Additionally, four simple beams without any external steel cable were also tested with material from the same lot of wood, allowing a comparison in rupture. The results showed capacity gain of around 60% compared to a simple beam. Once the wire rope characteristics and anchoring are very important for structure response, some improvement suggestions for the efficiency of the cables are also presented.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1927-1939
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• 1995

An experimental investigation is conducted to find out the large scale coherent structures in the intermediate wake past a rotating cylinder with a single tripping wire attached. Relation between the vortex shedding frequency and the spin rate of rotating cylinder and the effects of the tripping wire on the flow characteristics were studied by using spectral analysis and conditional phase average technique, respectively. It is found that the vortex shedding frequency is bound to a certain range and varies regularly as spin rate increases. The coherent structures are compared with those of the plain rotating cylinder in the case of spin rate of 1.0. Distance between the upper and lower center of vortices increase and the vortex shedding time is delayed, the velocity fluctuation energy decreases near the center line of vortices and it spreads out to the outer region. The Reynolds shear stress increases highly in the upper region and the turbulent wake width expands with strong entrainment process.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.13-19
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• 2008

A Wire-woven Bulk Kagome (WBK) is the new truss type cellular metal fabricated by assembling the helical wires in six directions. The WBK seems to be promising with respect to morphology, fabrication cost, and raw materials. In this paper, first, the geometric and material properties are defined as the main design parameters of the WBK considering the fact that the failure of WBK is caused by buckling of truss elements. Taguchi approach was used as statistical design of experiment(DOE) technique for optimizing the design parameters in terms of maximizing the compressive strength. Normalized specific strength is constant regardless of slenderness ratio even if material properties changed, while it increases gradually as the strainhardening coefficient decreases. Compressive strength of WBK dominantly depends on the slenderness ratio rather than one of the wire diameter, the strut length. Specifically the failure of WBK under compression by elastic buckling of struts mainly depended on the slenderness ratio and elastic modulus. However the failure of WBK by plastic failed marginally depended on the slenderness ratio, yield stress, hardening and filler metal area.